The name Treo has become synonymous with smartphone in the Palm world, going back to the original Treo 180 and then onto the Treo 270 and the Treo 300. While these devices worked well, they really only scratched the surface of what a PDA and cellphone combination device could do.

The Treo 600 is a vast improvement. The best Palm OS smartphone we've come across. While there are smaller smartphones in other platforms, such as Motorola, Samsung and Orange's Windows Smartphones, none offer the breadth of application support or the degree of integration that the Treo 600 does. The Treo 600's chief competition in the Palm OS world is the Samsung SPH-i500, a smaller device without a keyboard that leans more heavily towards the phone part of the PDA/Phone equation.

Treo 600 comes in two flavors, a CDMA edition for the Sprint network and a GSM/GPRS edition that is offered by AT&T, Cingular and T-Mobile. We took a look at the GSM version running on Cingular's network.

The Treo 600 has solid PDA specifications. It runs a modified version of Palm OS 5.2.1 which has been altered by Handspring (now a part of PalmOne) to work better in a phone environment. The Address Book, for instance, is noticeably geared more towards cellphone use, and in fact is a nice improvement over the standard Palm OS Address Book.